We are interested in chemically characterizing the unique human body odors which arise from the action of resident microorganisms on the secretions from the apocrine and sebaceous glands. These two glands provide the substrate for formation of axillary and scalp odors. Progress has been made in understanding the mechanism of axillary odor formation. Two distinct odor qualities have been correlated with specific bacterial populations. The discovery of two androgen steroids in the apocrine secretion demonstrates that these steroids and cholesterol, previously found in the axillary skin surface, are secreted by the apocrine gland. We wish to determine the odorants produced when the diphtheroid bacteria are incubated on apocrine secretion. The possibility that these bacteria are capable of metabolizing androgen steroids and can synthesize odorous delta 16-steroids is being investigated by direct steroid analysis and by changes in the substrate involving specific enzymes and/or steroid precursors. The development of a selective and sensitive detection method for the presence of apocrine secretion and/or axillary odorants will enable one to monitor a stress-induced secretion. We also wish to determine the volatile metabolites produced by various cutaneous microorganisms using headspace concentration from specific growth media combined with gas chromatographic/mass spectrometric analyses. These metabolic profiles, if unique to a given genus, can serve as an aid in taxonomic classification.